Full-duplex (FD) communication is a promising technology for increasing the wireless capacity of wireless sensor networks (WSNs) for Internet of Things (IoT) services. However, the theoretical throughput gain of FD is difficult to achieve under erroneous channel conditions. Given this problem, we presents an early error detection strategy (EEDS) to maximize the spectral efficiency of the FD relaying system in WSNs. To reduce frame retransmission due to bit errors, the EEDS divides the entire medium access control (MAC) service data unit (MSDU) of the frame into several fragments and separately inspects each of them on the receiver side. To verify the effectiveness of EEDS, simulations were conducted under various conditions with variations in bit error rate, the number of fragments, and the size of the MSDU. The results show that the throughput and delay performance of the EEDS can be significantly improved under erroneous channel conditions.